Manufacture of incandescent electric lamps



no Mddel.) J I I T. A.- EDISON. H

MANUFACTURE OF INGANDESUENT ELEGTRIG L AMPS."

Nd.406,130 Patented JuIy 2, 1 889.

TFT W NP Q,

specification.

STATES i PATENT: OFF-ICE;

'. THOMAS A. EDISON, OE LL' wE LYn PARK, NEW JERSEY.

i j-MANUFAGTURETOF- INCANDESCEINT YEIQEGTRICJ'LAMPS.

' SPECIFICATION forming'part of Letters Patent No. 406,130, dated July 2, 1889.

Application filed August 11 1886.

To all whom it may concern:

Be it known that I, THOMAS A. EDISON, of Llewellyn Park, in thecounty' of Essex. and State of New Jersey, have invented a certain new and useful Improvementin Incandescent Electric Lamps and the Manufacture thereof, (Case No. 678,") of which the following is a r The object, of my invention is to so construct an incandescent electric lamp that the electrical carrying or transporting'of car :bon particles from the filament to the glass will be greatly diminished or entirely prevented. This electrical carrying occurs ordinarily, and results in the blackening of the globe and the shortening of the life of the filament. I accomplish this by coating the semi liquid conducting-film. .used' is of such character that it will not give flofi gases injurious to the filament at the terriperat'ure given to the globe by the incandesinner surface of the globe with a conducting material-via; a 'thintransparent adhesive The material cenceof the filament. If the inner surface of the globe is a conductor, it will be of an electrical potential about the same as that of the filament, and consequently there will belittle or no tendency for the carbon particles to pass from the filament to the glass.

The substance with which I prefer to coat the glass is melted phosphoric anhydride con taining just enough water to make it run over the glass. This is a transparent gummy .substance, and does not give 01f its water or any gases. at the temperature to which the globe is raised in the use of the lamp. I This substance may be introduced into the globe and allowed to run all over the glass by moving and turning the globe, so that it leaves, a thin film upon the entire surface.

' Where the globe is small and the filament comes close to the glass, so that the glass is more highly heated thereby, I combine a smaller amount of Water with the phosphoric anhydride, so that it may not run freely, and in this case I employ the following method for producing the film upon the glass.

A piece of glass inclosing a piece of iron is placed in the globe, together with a piece of phosphoric anhydride, and the proper amount of water is added to the latter by means of a narrow glass tube passed through Serielll'o. 210,6(17. (N0 model.)-

to the lamp the poles of a sufficiently-power ful electro-magnet the piece of glass and iron is moved into the mass of phosphoric anhy dride, and then the piece of glass is moved. all

over the interior of the lamp, being brought back to the phosphoric anhydridefor a fresh supply when necessary. A very thin coating is'th'us produced upon the glass of the lamp. The piece of glass and iron is then removed, and the lamp is;now ready for exhaustion.

Where a considerablequantity of waterenough to make it rlin -is added to the phos phoric anhydride,"thelamp should be externally heated before exhaustion to a tempera,- ture greater than that to which it will be brought 'in use, to make the phosphoric anhydride give'up all the moisture which canbe driven from it.; The lamp may then be dried in any suitable manner.

Other substances than that mention'ed m ay be usedfor'instance, chloride of zinc, and, for low-temperature lamps, pure sulphuricacid.

In the accompanying drawings, Figure 1 shows" the process of producing the film by means of a magnet, and Fig. 2 an enlarged" sectionof a partof the globe of theiampembodying my invention. i

A is the lamp. f B is the electro-magnet; c, the piece of glass inclosing iron d, the piece of phosphoric anhydride, and e the tube for introducing water.- 0 is the thin transparent adhesive conducting-filniproduced by-eitherof the processes described.

What I claim is- 1. The combination, with ;the globe of an incandescent electric lamp, and the filament inclosed thereby, of a transparent conductingfilm on the interior of said ti'ally as set forth.

2. The combination, with an incandescent electric-lamp globe and the filament inclosed thereby,'of a transparent adhesive conducting-film on -the-in.terior of said globe, substantially asset forth.

3. The combination, with an incandescent electric-lamp globe and the filament inclosed globe, substanthereby, of a film of adhesive phosphoric anstance by external magnetic attraction, subhydride on the interior of said globe, substant-ially as set forth. IO stantially as set forth. K This specification signed and witnessed.

4., The method of producing a coating on this 6th day of August, 1886.

the interior of an incandescent electric-lamp v THOS. A. EDISON. globe, consisting in placing an adhesive semi- Witnesses: liquid substance within said globe and mov- WM. PELZER, ing a magnetic body into and out of said sub- E. C. -ROWLAND. 

